MFC r284915:
Make the system queue header file fully usable within C++ programs by
adding macros to define class lists.

This change is backwards compatible for all use within C and C++
programs. Only C++ programs will have added support to use the queue
macros within classes. Previously the queue macros could only be used
within structures.

The queue.3 manual page has been updated to describe the new
functionality and some alphabetic sorting has been done while
at it.

Differential Revision: https://reviews.freebsd.org/D2745
PR: 200827 (exp-run)